Railway signal control system



1939. .J. B. GRIFFITHS El AL 2,182,122

RAILWAY SIGNAL CONTROL SYSTEM Filed Sept. 9, 1936 INVENTOR JOHN B GRlFFl'fi-IS ANDREW BROWN ATTORNE AMI! Patented Dec. 5, 1939 stares PATENT 'OFFIQCE RAILWAY SIGNAL CONTROL SYSTEM Application September 9, 1936, Serial N0. 99,939 In Great Britain September 13, 1935 8 Claims.

This invention relates to railway or like automatic signal or points control systems of the kind in which the signal and/or points for a particular section of track isor are automatically controlled by the automatic counting of the number of wheels on a train as the train enters a section and as the train leaves the section. In such systems a signal is set to danger on the train entering a section and only permitted to indicate that the track is clear if the same number of wheels has been automatically counted out of the section, as was automatically counted into the section.

The term signal is to be understood as including any locking means therefor, while the term points is to be understood as including any locking means therefor. The signals may be operated in a fully automatic manner, or may be automatically put to danger when a wheel enters 90 a section and locked in such position until the indication that the section is clear is received, after which the signal may be manually returned to clear.

The control of points consists in the prevention of any attempted alteration of the points whilst a train is still in the section.

In such systems, directional treadles have previously been proposed to take care of cases in which movement of a train over a track section may take place in both directions, such treadles operating two sets of counting means. It is also known to provide at each end of a section a large number of contacts to be operated successively by a wheel, and to send a signal into the counting equipment only when all the contacts have been actuated. Thus if a wheel reverses before actuating the last contact it is not counted. This known arrangement is reversible so that a wheel closing the contacts in succession in one direction is counted into the section, whilst if the contacts are operated in the reverse direction it is counted out.

The invention comprises an arrangement in which two sets of contacts only are provided at each end of a section, but in which nevertheless reversal of movement of a wheel whilst passing the contacts is detected and correct signals sent to the counting apparatus.

The invention and the manner in which the same to be performed will be clear from the following description of one embodiment thereof taken in conjunction with the accompanying drawing which shows diagrammatically pivoted treadles X, Y at one end of a track section, pivoted treadles X Y at the other end of the track sec tion and the relays and equipment controlled thereby. The treadles lie parallel to the track, and in such relation thereto that the wheels of passing cars depress them, treadles X and Y and X and Y respectively overlapping. A wheel passing in either direction depresses first one treadle, then both treadles, then releases the first treadle but still depresses the second and finally releases the second treadle.

The treadles X and Y when depressed open the circuits of relays A and B respectively and similarly treadles X and Y control the circuits of relays A and B. The arrangements at both ends of the track are similar and consequently corresponding relays and contacts at the right hand side are denoted by the same reference characters as those on the left but with the addition of a prime jointly control equipment contained in the rectangle marked SAC' for receiving in-coming and out-coming impulses and for controlling the signals and/or points accordingly. Positive battery is normally connected to the terminal marked I to which is connected the in-counting relay (not shown). Similarly positive battery is normally connected to the terminal marked t to which is connected the out-counting relay (not shown). Both these relays are accordingly normally energised. A break in the circuit of either of them is therefore an impulse, in-counting or out- U counting as the case may be. The details of construction of the equipment SAC form no part of this invention andv accordingly this equipment is not further described.

All relays are shown energised on the drawing, 3

which is their normal condition and the contacts are shown in normal position, the letters a, 22, ab, etc., on the contacts indicate they are controlled byrelays A, B, AB, etc., respectively, and the numerals indicate the contact number. contact arms controlled by the separate relays are shown in a horizontal position to indicate that they are operated. When the relays are deenergized the contacts assume a slanting posi- I The The two sets of relays presses the arm X and so releases the relay A. The opening of contact at simultaneously deenergises the relays AB and AR.

The relay AB is a high speed relay which immediately releases, but the relay AR is a slow releasing relay which does not release in the case of a rapid train. The release of contacts at? does not afiect the circuit for BA since contacts but are in parallel with at. The wheel then passes on, depresses the arm Y and releases the relay B. The release of contact bl has no effect on the circuit since those contacts have previously been paralleled by contacts ao'2.- The release of contacts b2 has no. immediate eifect, since the relay AB is de-energised. in any case. When the wheel leaves the arm X relay A is re-energised. Relay AB, however, is notre-energised because contacts chi and D2 .are both open. When the wheel leaves the arm Y relay B is re -operated and thereafter relay AB is operated over contacts cal and b2 so that all relays have returned to their normal condition.

The momentary release of the relay AB which took place during the above cycle of operations caused a disconnection in the circuit of the incounting relay of the equipment SAC at contacts a293, so that one wheel was duly counted into the section.

In the same way, if a wheel moves rapidly out 'of the section at the right hand end, the relay AB is momentarily released and the interruption on contacts aba steps the out-counting relay. A wheel entering the section from the right, depresses treadle Y and de-energises relay B, which at its contacts bl de-energises BA which at contacts ba3 sends an in-counting impulse. On leaving the section relay BA is de-ener'gised to send an out-counting impulse.

Consider now the case of awheel which moves over the treadle sufliciently slowly to render a reversal of direction possible but which passes over the treadle without reversal. The relays A and AB would be de-energised as before and an in-counting impulse would be recorded. Relay A would be de-energised for sufiicient time to permit relay AR to release. The release of relay B would have no immediate effect and as the wheel moves slowly from the treadle X, contacts al would reclose and would have ample time to re-energize the relay AR before the wheel finally passed off treadle Y, re-energising relays B and AB.

It should be noted, therefore, that although the relay AR is released its release period is ventirely covered by that of relay AB. The movement of contacts ari disconnects the normal positive supply to the out-counting relay, but during the time that the relay AB is released this positive supply is confirmed over the contacts 11114. The net result of this slow speed cycle is, therefore, a single in-counting impulse. Similar slow speed cycles can be traced in either direction over either treadle.

Consider now the case of a wheel which moves slowly over the treadle and reverses its direction just before it leaves the arm Y. On the first release of relays A and AB one in-counting impulse is sent to SAC as before, thereafter relay AR would be released and re-energized when the wheel passed off from the arm' X. Before re-energizing relays B and AB the wheel would then reverse, depressing the arm X once more and so releasing the relay AR once more. The wheel then leaves arm Y, re-energizing relay B, contact b2 prepares a circuit for the relay AB which, however, remains open circuited at contacts al.

When the wheel finally leaves arm X contacts al reclose and relays AB and AR are simultaneously energised.

Since the relay AR is made slow to operate contacts arl will remain open after the contacts ab i have been re-opened and during this period an out-counting impulse is sent. It will be seen, therefore, that the standard unit has performed an in-counting movement when the wheel first touched the treadle and an out-counting movement when the same wheel reversed off the treadle, the net result being that the wheel has not been counted into the section. Similar slow speed reverse movements can be traced in either direction over either treadle.

It will be observed that the arrangement described permits an out-counting impulse to be sent in immediate succession to an in-counting im ulse (or vice versa) by the same treadle in the case of a reversal of a wheel travelling at a speed slow enough to keep the circuit of relay AR or BR broken for sufiicient time for it to de-energise. A wheel which gives rise to two different impulses in succession, must, however be travelling at a speed low enough for such reversal to happen, and it would be impossible for a wheel travelling over the treadle at a speed too high to allow AR (or BR) to break its contacts, to reverse its direction of movement whilst actually on the treadle.

It is clear also that the arrangement described allows a wheel to be counted out of the section at one end thereof simultaneously with the incounting of another wheel at the other end thereof. For example in the case of wheels travelling from left to right on the drawing, wheels leaving the section could be counted out by the opening of contacts ab3 independently of and simultaneously with the counting of wheels into the section by the opening of contacts ab3. The sending of out-counting impulses by contacts ab3 is not interfered with by operation of contacts ab l which takes place if in-counting impulses are simultaneously sent by the operation of contacts ab3. Similarly, the operation of contacts D113 is not interfered with by the closing of contacts biz/4 which takes place if in-counting impulses are simultaneously sent by the operation of contacts ba'3.

- What is claimed is:

l. A railway or like automaticsignal or points control system, comprising a track section, two pairs of contacts arranged for successive and overlapping operation in one of two orders, wheel operated means for operating said contact pairs in one or the other of said orders dependent upon whether a wheel passes in a forward or reverse direction over said wheel operated means, equipment for controlling signals or points, signalling means controlled by said contact pairs for sending into said equipment impulses for counting wheels into or out of said section depending on the order in which said pairs of contacts are operated for controlling said equipment to ensure correct control of said signals or points, means controlled by said pairs of contacts for detecting reversal of direction of a wheel whilst passing said wheel operated means, and means controlled by said detecting means for operating said signalling means to ensure correct control of the signals or points by said equipment in event of such a reversal in direction.

2. A railway or like automatic signalor points control system as claimed in claim l in which said means controlled by said detecting means comprises contact controlled means for sending into said equipment an impulse for counting a wheel into said track section followed by an impulse for counting a wheel out of said track section or vice versa in the case of said reversal of direction.

3. A railway or like automatic signal or points control system comprising a track section, wheel operated means at one end thereof, control equipment for controlling signals or points, signalling means controlled by said wheel operated means for sending into said control equipment impulses for counting wheels into said section in response to passage of a wheel over said Wheel operated means in one direction and other impulses for counting wheels out of said section in response to p ssage or" a wheel over said wheel operated means in the reverse direction, direction reversal detecting means controlled by said Wheel operated means for detecting reversal of direction of movement of a wheel when passing said wheel operated means, and means controlled by said Wheel operated means for bringing into operation aid direction reversal detecting means in response to the condition that the speed of motion of a wheel is low enough to render such reversal possible.

i. A system as claimed in claim 3 in which said wheel operated means comprises two relays, circuits for said relays, means for breaking the circuits of said relays in succession and in over lapping relation, and said direction reversal detecting means comprises two slow releasing relays operatively associated with said first named relays each adapted to release in response to the condition that the circuit of said first mentioned relays is broken for greater than a predetermined time.

5. A system as claimedin claim 1 comprising other wheel operated means and means controlled thereby at the other end of the said section, said last named means being connected with said signalling means to send signals to said control equipment for counting wheels into and out of said section.

6. A railway or like automatic signal or points control system comprising a track section, a single main control equipment for counting the number of wheels entering and leaving the section, and for controlling signals or points accordingly, separate normally closed Wheel operated impulsin'g contacts at each end of the section operative in successive overlapping relation for operating said main control equipment, separate auxiliary equipment cooperating with said contacts at each end of. said section for sending to the said control equipment impulses indicating the number of wheels entering the section irrespective of the particular end of the section at which they enter and impulses indicating the number of wheels leaving the section irrespective of the particular end of the section at which they leave.

'2. A system as claimed in claim 1 in which said Wheel operated means comprises pivoted treadles one for each contact pair arranged parallel to the track and in overlapping relation, said treadles being depressed by the passage of a wheel thereover.

8. A railway or like automatic signal or points control system comprising two pair of normally closed wheel operated impulsing contacts situated at the end of a track section, said contacts being arranged for successive overlapping operation in one of two orders dependent upon the direction of passage of a wheel thereover, and

signal transmitting means operatively associated with said contacts for transmitting signals dependent upon the order of operation of said contacts.

JOHN BALMAIN GRIFFITHS. ANDREW BROWN. 

